U.S. Pat. No. 6,581,638 describes a valve with a compact piezoelectric flexural transducer unit, comprising two at a pivot bearing jointly connected flexural elements with a common carrier layer. The flexural transducer unit comprises an enlarged valve lift compared to a simple flexural transducer. As another advantage of this configuration it is shown in U.S. Pat. No. 6,581,638 that due to the pivot bearing and the identical structure of the two flexural elements an automatic compensation of temperature-related deformations of the flexural elements occurs as a result. Compared to conventional piezoelectric flexural elements the double overall width is however disadvantageous, which e.q. is unfavorable for use in valve arrays with low channel spacing. The technically complex fabrication of the flexural transducer unit is further disadvantageous.
To compensate for slow deformations caused by temperature changes, aging, mechanical strain or creep it is proposed in EP 148 630 to insert a power transmission device into the path of power transmission between the moving end of an actuator and a working device, the power transmission device allowing to almost fully transfer the movement of the actuator. The power transmission device includes a power transmission element, which the actuator is associated with, a force receiving element, which the working device is associated with and a viscous liquid in a gap between the transmission element and the force receiving element, which behaves hard in case of fast actuator deflections, but which does not transfer slow-running parasitic movements to the working device.
In EP 148 630 it is further mentioned, that the described power transmission device is principally applicable within a valve comprising a bimorph piezoelectric flexural transducer. So according to EP 148 630 the proposed power transmission device would be installed between the moving end of a piezoelectric flexural transducer and e.g. a valve closure element. When applied to a miniature valve system with driving forces below 50 mN the total mass of the transmission device would have to be moved, so the switching times would be influenced strongly negative. Also most delicate fabrication and assembly steps would have to be carried out.